Identical Twins Reared Apart


Identical twins reared apart constitute two individuals with the same genetic constitution (genotype) reared in two different environments. The study of a series of such twins allows us to estimate the influence of genetic and environmental factors on measured characteristics (phenotypes) of the twins. Studies of twins reared apart have consistently confirmed the findings of studies of twins reared together, which have demonstrated moderate genetic influence on virtually all reliably measured psychological traits.

Keywords: monozygotic; dizygotic; twins; adoption; behavior genetics

Further Reading

Bouchard Jr TJ and Pedersen N (1999) Twins reared apart: nature's double experiment. In: LaBuda MC and Grigorenko EL (eds.) On the Way to Individuality: Methodological Issues in Behavioral Genetics, pp. 71–93. Commack, NY: Nova Science Publishers

Galton F (1876) The history of twin, as a criterion of the relative powers of nature and nurture. Journal of the Anthropological Institute of Great Britain and Ireland 5: 391–406.

Juel‐Nielsen N (1980) Individual and Environment: Monozygotic Twins Reared Apart. New York, NY: International Universities Press. [Revised edition of 1965 monograph.]

Langinvainio H, Kaprio J, Koskenvuo M and Lonnquist J (1984) Finnish twins reared apart. III. Personality factors. Acta Geneticae Medicae et Gemellologiae 33: 259–264.

Mackintosh NJ (ed.) (1995) Cyril Burt: Fraud or Framed?. Oxford, UK: Oxford University Press.

Martin N, Boomsma D and Machin G (1997) A twin‐pronged attack on complex traits. Nature Genetics 17: 387–392.

Newman HH, Freeman FN and Holzinger KJ (1937) Twins: A Study of Heredity and Environment. Chicago, IL: University of Chicago Press.

Pedersen NL, Plomin R, Nesselroade JR and McClearn GE (1992) A quantitative genetic analysis of cognitive abilities during the second half of the life span. Psychological Science 3: 346–353.

Shields J (1962) Monozygotic Twins: Brought Up Apart and Brought Up Together. London, UK: Oxford University Press.

Teasdale TW and Owen DR (1984) Heritability and familial environment in intelligence and educational level: a sibling study. Nature 309: 620–622.

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How to Cite close
Bouchard Jr, Thomas J(Jul 2006) Identical Twins Reared Apart. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0005156]